Light emitting device, light emitting device package, and lighting system

ABSTRACT

Provided are a light emitting device, a light emitting device package, and a lighting system. The light emitting device includes a substrate, a light emitting structure layer, a second electrode, a first electrode, a contact portion, and a first electrode layer. The first electrode is disposed in the substrate from a lower part of the substrate to a lower part of a first conductive type semiconductor layer in a region under an active layer. The contact portion is wider than the first electrode and makes contact with the lower part of the first conductive type semiconductor layer. The first electrode layer is disposed under the substrate and connected to the first electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119(a) ofKorean Patent Application No. 10-2010-0034862 filed on Apr. 15, 2010,which is hereby incorporated by reference in its entirety.

BACKGROUND

Embodiments relate to a light emitting device, a light emitting devicepackage, and a lighting system.

Due to physical and chemical characteristics, group III-V nitridesemiconductors are being considered as core materials for light-emittingdevices such as light-emitting diodes (LEDs) and laser diodes (LDs).Generally, group III-V nitride semiconductors are formed of asemiconductor material having a compositional formula ofIn_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1).

LEDs are a kind of semiconductor device that is used as a light sourceor used to transmit a signal by converting electricity into infraredrays or light by using the characteristics of compound semiconductors.

Such LEDs or LDs using a nitride semiconductor material are widely usedas light-emitting devices. For example, LEDs and LDs are widely used aslight sources of various products such as keypad light-emitting units ofcellular phones, electric displays, and lighting devices.

SUMMARY

Embodiments provide a light emitting device having a new electrodestructure.

Embodiments provide a light emitting device including a growth substrateand a vertical electrode structure.

Embodiments provide a light emitting device including a first electrodedisposed under a region of an active layer and a second electrodedisposed on a region of the active layer.

Embodiments provide a light emitting device, a light emitting devicepackage, and a lighting system that are more reliable.

In one embodiment, a light emitting device including: a substrate; alight emitting structure layer comprising a first conductive typesemiconductor layer, an active layer on the first conductive typesemiconductor layer, and a second conductive type semiconductor layer onthe active layer; a second electrode on the light emitting structure; afirst electrode disposed in the substrate and extended from a lower partof the substrate to a lower part of the first conductive typesemiconductor layer, the first electrode being disposed under a regionof the active layer; a contact portion having a width wider than a widthof the first electrode disposed in the substrate and disposed at thelower part of the first conductive type semiconductor layer; and a firstelectrode layer disposed under the substrate and connected to the firstelectrode.

In another embodiment, a light emitting device including: a transmittivesubstrate; a first electrode layer under the substrate; a light emittingstructure layer comprising a first conductive type semiconductor layer,an active layer on the first conductive type semiconductor layer, and asecond conductive type semiconductor layer on the active layer; aplurality of first electrodes disposed in the substrate and extendedfrom the first electrode layer to a lower part of the first conductivetype semiconductor layer; a second electrode layer on the light emittingstructure layer; a second electrode on the second electrical layer; anda contact portion contacted with the lower part of the first conductivetype semiconductor layer disposed under the active layer and having awidth different from a width of the first electrode disposed in thesubstrate.

In further another embodiment, a light emitting device packageincluding: a body; a plurality of lead electrodes on the body; a lightemitting device on at least one of the lead electrodes; and a moldingmember covering the light emitting device, wherein the light emittingdevice includes: a substrate;

a light emitting structure layer comprising a first conductive typesemiconductor layer, an active layer on the first conductive typesemiconductor layer, and a second conductive type semiconductor layer onthe active layer; a second electrode on the light emitting structure; afirst electrode disposed in the substrate and extended from a lower partof the substrate to a lower part of the first conductive typesemiconductor layer, the first electrode being disposed under a regionof the active layer; a contact portion having a width wider than a widthof the first electrode disposed in the substrate and disposed at thelower part of the first conductive type semiconductor layer; and a firstelectrode layer disposed under the substrate and connected to the firstelectrode.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features will be apparent fromthe description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view illustrating a light emitting deviceaccording to a first embodiment.

FIG. 2 is a plan view illustrating the light emitting device of FIG. 2.

FIGS. 3 to 7 are views for explaining processes of manufacturing thelight emitting device of FIG. 1.

FIG. 8 is a side sectional view illustrating a light emitting deviceaccording to a second embodiment.

FIG. 9 is a side sectional view illustrating a light emitting deviceaccording to a third embodiment.

FIGS. 10 and 11 are views for explaining processed of manufacturing alight emitting device according to a fourth embodiment.

FIGS. 12 to 14 are views for explaining processes of manufacturing alight emitting device according to a fifth embodiment.

FIG. 15 is a view illustrating a light emitting device according to asixth embodiment.

FIG. 16 is a side sectional view illustrating a light emitting deviceaccording to a seventh embodiment.

FIG. 17 is a side sectional view illustrating a light emitting deviceaccording to an eighth embodiment.

FIG. 18 is a view illustrating a light emitting device package accordingto an embodiment.

FIG. 19 is a diagram illustrating a display device according to anembodiment;

FIG. 20 is a diagram illustrating another display device according to anembodiment; and

FIG. 21 is a diagram illustrating a lighting device according to anembodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the descriptions of embodiments, it will be understood that when alayer (or film), a region, a pattern, or a structure is referred to asbeing on a substrate, a layer (or film), a region, a pad, or patterns,it can be directly on another layer or substrate, or intervening layersmay also be present. Further, it will be understood that when a layer isreferred to as being ‘under’ another layer, it can be directly underanother layer, and one or more intervening layers may also be present.Further, the reference about ‘on’ and ‘under’ each layer will be made onthe basis of drawings.

Hereinafter, exemplary embodiments will be described with reference tothe accompanying drawings. In the drawings, the thickness or size ofeach layer is exaggerated, omitted, or schematically illustrated forconvenience in description and clarity. Also, the size of each elementdoes not entirely reflect an actual size.

Hereinafter, exemplary embodiments will be described with reference tothe accompanying drawings.

FIG. 1 is a side sectional view illustrating a light emitting device 100according to a first embodiment, and FIG. 2 is a plan view illustratingthe light emitting device 100 of FIG. 1.

Referring to FIG. 1, the light emitting device 100 includes a substrate101, a first conductive type semiconductor layer 110, an active layer115, a second conductive type semiconductor layer 120, second electrodeparts 150 and 152, a first electrode 160, and a first electrode layer165.

The light emitting device 100 includes a light emitting diode (LED)including a plurality of compound semiconductor layers such as groupIII-V compound semiconductor layers. The LED may be a light emittingdiode chip emitting visible light such as blue, green, or red light oran ultraviolet (UV) light emitting diode chip emitting ultravioletlight. The light emitting diode chip may emit light by using a varietyof semiconductors in the technical scope of the embodiment.

The substrate 101 is an insulating or conductive growth substrate onwhich a compound semiconductor can be grown. The substrate 101 may beformed of a material selected from the group consisting of Al₂O₃(sapphire), GaN, SiC, ZnO, Si, GaP, InP, Ga₂O₃, and GaAs. In theembodiment, the substrate 101 may be an insulating substrate such as asapphire substrate, and the insulating substrate may be a transmittivesubstrate.

A light extracting structure disposed on the substrate 101 may include aconcave-convex structure or a rough structure. The thickness of thesubstrate 101 may be at least ten times the thickness of a lightemitting structure layer 125. For example, the thickness of thesubstrate 101 may be in the range from about 50 μm to about 500 μm. Ifthe substrate 101 is formed of a transmittive material, light emittingangle can be improved.

In addition, the substrate 101 may include a material the latticeconstant of which is different from the lattice constant of the compoundsemiconductor layers. However, the substrate 101 is not limited thereto.

At least one compound semiconductor layer may be disposed between thesubstrate 101 and the first conductive type semiconductor layer 110. Thecompound semiconductor layer may be a layer or pattern formed of a groupII to VI compound semiconductor such as ZnO, GaN, AlN, AlGaN, InGaN,InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, or AlGaInP. For example,the compound semiconductor layer may include a buffer layer and/orundoped semiconductor layer, and the buffer may reduce the latticeconstant difference between the compound semiconductor and the substrate101. For example, the undoped semiconductor layer is a nitride-basedsemiconductor layer in which a conductive type dopant is notintentionally doped. The undoped semiconductor layer may be asemiconductor layer having significantly low conductivity than that ofthe first conductive type semiconductor layer 110. For example, theundoped semiconductor layer may be an undoped GaN layer and have a firstconductive type characteristic.

The first conductive type semiconductor layer 110 is disposed on thesubstrate 101 or the compound semiconductor layer. The first conductivetype semiconductor layer 110 is disposed between the substrate 101 andthe active layer 115, and the active layer 115 is disposed between thefirst conductive type semiconductor layer 110 and the second conductivetype semiconductor layer 120. Another semiconductor layer may be furtherdisposed on or under each of the layers. However, the embodiment is notlimited thereto. Here, the other semiconductor layer includes a layer,which has a different composition constituted by group III-V elements ora different conductive type dopant concentration.

The light emitting structure layer 125 includes the first conductivetype semiconductor layer 110, the active layer 115, and the secondconductive type semiconductor layer 120.

The first conductive type semiconductor layer 110 may be formed of agroup III-V compound semiconductor doped with a first conductive typedopant, such as GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs,GaP, GaAs, GaAsP, or AlGaInP. The first conductive type semiconductorlayer 110 may be formed of a semiconductor material having acompositional formula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1,0≦x+y≦1). The first conductive type semiconductor layer 110 may be anN-type semiconductor layer. The N-type semiconductor layer includes anN-type dopant such as Si, Ge, Sn, Se, or Te. The first conductive typesemiconductor layer 110 may be formed in a single- or multi-layerstructure, but is not limited thereto.

The first conductive type semiconductor layer 110 may have a superlattice structure (SLS) in which different semiconductor layers arestacked. The super lattice structure may include a structure such as aGaN/InGaN structure or a GaN/AlGaN structure. The super latticestructure may include a structure in which at least two pairs ofdifferent layers each having a thickness of about several angstroms (Å)or more are alternately stacked.

The width of the first conductive type semiconductor layer 110 may beequal to or greater than the width of the active layer 115, and equal toor smaller than the width of the substrate 101. Here, at least one sideof the light emitting structure layer 125 may be spaced apart from aside of the substrate 101 by a predetermined distance D1, and an outerregion of the topside of the substrate 101 may be opened. The firstconductive type semiconductor layer 110 may be thicker than at least theactive layer 115.

The active layer 115 is disposed on the first conductive typesemiconductor layer 110, and the active layer 115 may has at least oneof a single quantum well structure, a multi quantum well structure, aquantum wire structure, and a quantum dot structure. The active layer115 may be formed of a group III-V compound semiconductor material andinclude a period of well layer/barrier layer. For example, the activelayer 115 may include at least one of a period of InGaN well layer/GaNbarrier layer, a period of InGaN well layer/AlGaN barrier layer, and aperiod of InGaN well layer/InGaN barrier layer.

A first conductive type clad layer may be disposed between the firstconductive type semiconductor layer 110 and the active layer 115. Thefirst conductive type clad layer may be formed of a GaN-basedsemiconductor. The first conductive type clad layer may have a band gapgreater than that of the barrier layer within the active layer 115 andfunction to confine carriers.

A second conductive type clad layer may be disposed between the activelayer 115 and the second conductive type semiconductor layer 120. Thesecond conductive type clad layer may be formed of a GaN-basedsemiconductor. The second conductive type clad layer may have a band gapgreater than that of the barrier layer within the active layer 115 andfunction to confine carriers. The width of the active layer 115 may besmaller than that of the substrate 101.

The second conductive type semiconductor layer 120 is disposed on theactive layer 115. The second conductive type semiconductor layer 120 maybe formed of a group III-V compound semiconductor doped with a secondconductive type dopant, such as GaN, AlN, AlGaN, InGaN, InN, InAlGaN,AlInN, AlGaAs, GaP, GaAs, GaAsP, or AlGaInP. The second conductive typesemiconductor layer 120 may be formed of a semiconductor material havinga compositional formula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1,0≦x+y≦1).

The second conductive type semiconductor layer 120 may have a single- ormulti-layered structure. When the second conductive type semiconductorlayer 120 has a multi-layered structure, the second conductive typesemiconductor layer 120 may have a super lattice structure such as anAlGaN/GaN structure or a stacked structure of layers having differentdopant concentrations.

The second conductive type semiconductor layer 110 may be a P-typesemiconductor layer. The P-type semiconductor layer includes a P-typedopant such as Mg, Be, or Zn. The second conductive type semiconductorlayer 120 may function as an electrode contact layer, but is not limitedthereto. The topside of the second conductive type semiconductor layer120 may has a rough structure, but is not limited thereto.

In addition, a third conductive type semiconductor layer having apolarity opposite to that of the second conductive type may be disposedon the second conductive type semiconductor layer 120. The lightemitting structure layer 125 may have at least one of an N—P junctionstructure, a P—N junction structure, an N—P—N junction structure, and aP—N—P junction structure. Here, N denotes an N-type semiconductor layer,P denotes a P-type semiconductor layer, and ‘-’denotes a directly orindirectly stacked structure of two semiconductor layers. Hereinafter, astructure in which the second conductive type semiconductor layer 120 isthe uppermost layer of the light emitting structure layer 125 will bedescribed as an example.

The second electrode parts 150 and 152 may be electrically connected tothe second conductive type semiconductor layer 120. The second electrodeparts 150 and 152 may be disposed on the second conductive typesemiconductor layer 120. The second electrode parts 150 and 152 includesa pad 150 and a second electrode 152 electrically connected to the pad150.

The second electrode parts 150 and 152 may be formed into a single layeror multi layers by using at least one selected from the group consistingof Ti, Al, Al alloy, In, Ta, Pd, Co, Ni, Si, Ge, Ag, Ag alloy, Au, Hf,Pt, Ru, Au, and an alloy thereof. The number of the pad 150 may be atleast one, and the width of the pad 150 may be greater than that of thesecond electrode 152. The second electrode 152 may extend from the pad150 at least in one direction.

The second electrode 152 may be electrically connected to the pad 150and have at least a branch, arm, or finger shape.

The pad 150 may be disposed at an edge side when viewed from a chip topside. Alternatively, the pad 150 may be disposed at a center part.

The second electrode 152 may branch from the pad 150 in a loop shape.The loop shape may be a closed or open loop shape. For example, thesecond electrode 152 may have one of the following pattern shapes: aradial pattern, at least one branch pattern, a curve pattern, a linearpattern, a polygonal pattern, a circular pattern, and a combinationthereof. However, the shape of the second electrode 152 is not limitedthere to

A second electrode layer formed of a material different from theabove-described semiconductor layers may be disposed between the secondelectrode parts 150 and 152 and the second conductive type semiconductorlayer 120. The second electrode layer may include any one of an ohmiclayer, a current diffusion layer, and a transmittive conductive layer.The second electrode layer may include a transmittive oxide or nitride.For example, the second electrode layer may be formed into asingle-layer or multilayer structure by using at least one selected fromthe group consisting of ITO (indium tin oxide), IZO (indium zinc oxide),IZTO (indium zinc tin oxide), IAZO (indium aluminum zinc oxide), IGZO(indium gallium zinc oxide), IGTO (indium gallium tin oxide), AZO(aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zincoxide), IrOx, RuOx, RuOx/ITO, Ni, Ag, Ni/IrOx/Au, and Ni/IrOx/Au/ITO.The second electrode layer may diffuse a current and supply the diffusedcurrent to the second conductive type semiconductor layer 120.

The second electrode 152 is disposed in an edge region of the secondconductive type semiconductor layer 120, and the edge region is spacedapart from a side S1 of the second conductive type semiconductor layer120 by a distance D3.

At least one first electrode 160 may be provided. For example, aplurality of first electrodes 160 may be disposed at predeterminedintervals under a light emitting region, for example, under the activelayer 115. In this case, a process of etching a part of the active layer115 may not be necessary to form the first electrode 160, and thus alight emitting may not be reduced.

The first electrode 160 may be formed of a metal including at least oneselected from the group consisting of Cu, Ti, Cr, Ta, Al, In, Pd, Co,Ni, Ge, Ag, and Au, but is not limited thereto.

A hole 105 is formed in the substrate 101. For example, the hole 105 maybe a via hole or a through hole penetrating the substrate 101 from thetopside to the lower side of the substrate 101. The hole 105 may have aline shape perpendicular to or oblique to the lower side of thesubstrate 101.

As many holes 105 as the number of the first electrodes 160 may beformed, and the first electrodes 160 may be disposed in the holes 105.The hole 105 may have a circular section or a polygonal section.

The first electrode 160 electrically connects the first conductive typesemiconductor layer 110 and the first electrode layer 165.

A contact portion 162 of the first electrode 160 may make contact withat least a lower part of the first conductive type semiconductor layer110. For example, the contact portion 162 may be embedded through thelower surface of the first conductive type semiconductor layer 110. Thelower surface of the first conductive type semiconductor layer 110 maybe a N-face and make contact with the contact portion 162.

If the first conductive type semiconductor layer 110 makes directcontact with the substrate 101, the lower surface of the contact portion162 of the first electrode 160 is disposed on the top surface of thesubstrate 101.

The diameter or width of the first electrode 160 disposed in thesubstrate 101 may be about 0.5 μm to about 50 μm. The diameter of widthof the contact portion 162 of the first electrode 160 may be differentfrom that of the first electrode 160 disposed in the substrate 101. Forexample, the diameter of width of the contact portion 162 of the firstelectrode 160 may be greater than that of the first electrode 160disposed in the substrate 101.

The diameter (or width) of the contact portion 162 of the firstelectrode 160 may be about 2 μm to about 50 μm, and the thickness of thecontact portion 162 may be about 10 Å to about 30000 Å. The contactportion 162 of the first electrode 160 may be thinner than at least thefirst conductive type semiconductor layer 110.

If a plurality of first electrodes 160 are provided, the firstelectrodes 160 may be connected to each other. The contact portions 162of the first electrodes 160 may be connected to each other through atleast two conductive layers, and the conductive layers may include ametal material which is more conductive than the above-describedsemiconductor layers.

The conductive layers may include a pattern having an arm structure, abranch structure, or a loop structure. The conductive layers may bedisposed on the lower surface of the first conductive type semiconductorlayer 110 and/or the top surface of the substrate 101, but are notlimited thereto.

As shown in FIG. 2, the first electrodes 160 may be distributed underthe light emitting structure layer 125, for example, under the secondconductive type semiconductor layer 120, to supply a current uniformly.FIG. 1 is a side sectional view taken along line A-A of FIG. 2.

The first electrodes 160 may be arranged at regular, random, orirregular intervals T1. The intervals T1 may be varied according tocurrent efficiency and the pattern of the second electrode 152.

The first electrodes 160 are spaced apart from a side of the lightemitting structure layer 125, for example, a side of the secondconductive type semiconductor layer 120 by a predetermined distance D2.Thus, the first electrodes 160 may be disposed in a region disposedunder the light emitting structure layer 125.

The pad 150 and the second electrode 152 may be closer to the edges ofthe second conductive type semiconductor layer 120 than to the center ofthe second conductive type semiconductor layer 120. In FIG. 2, the pad10 is disposed between corners. However, the pad 150 may be disposed ona corner, but is not limited thereto. For example, the second electrode152 may have one of the following pattern shapes: a radial pattern, atleast one branch pattern, a curve pattern, a linear pattern, a polygonalpattern, a circular pattern, and a combination thereof. However, theshape of the second electrode 152 is not limited there to.

The first electrodes 160 may be disposed closer to the second electrode152 than to a top center region of the second conductive typesemiconductor layer 120 to diffuse a current to the whole region. Thiselectrode arrangement structure may facilitate diffusion of a current toedge regions to improve internal quantum efficiency.

Referring to FIGS. 1 and 2, the distance between the contact portion 162of the first electrode 160 and the second electrode 152 may be smallerthan at least the thickness of the light emitting structure layer 125.

The contact portion 162 of the first electrodes 160 may be disposed in aregion overlapping with at least a portion of the second electrode 152or in a region outside the second electrode 152.

The first electrode layer 165 may be disposed under the substrate 101 toconnect the plurality of first electrodes 160.

The first electrode layer 165 may be formed of the same material as afirst electrode material or a material different from the firstelectrode material. The first electrode layer 165 may be formed of ametal material having 50% or greater reflectivity and may be used as areflection layer. The first electrode layer 165 may be formed into asingle-layer or multilayer structure by using a conductive material thateasily adheres to the substrate 101. The lower surface of the firstelectrode layer 165 may be smaller than at least the lower surface ofthe substrate 101 but great than at least the lower surface of the firstconductive type semiconductor layer 110 or the active layer 115.

The first electrode layer 165 may be disposed on the lower surface ofthe substrate 101 entirely or partially and be formed into a singlepattern or a plurality of patterns. However, the first electrode layer165 is not limited thereto.

A reflection layer may be further disposed between the substrate 101 andthe light emitting structure layer 125. The reflection layer may beformed as a distributed Bragg reflector (DBR) by stacking at least twogroup III-V compound semiconductor layers (AlN/GaN) having differentrefractive indexes in a super lattice structure (at least once period).The reflection layer may be formed of a different material according tosemiconductor crystal or growth conditions.

As shown in FIG. 1, in the case where the substrate 101 of the lightemitting device 100 having a vertical electrode structure istransmittive, the critical angle of light can be changed by adjustingthe thickness of the substrate 101, and thus light extraction efficiencycan be improved.

FIGS. 3 to 7 are views for explaining processes of manufacturing thelight emitting device of FIG. 1.

Referring to FIG. 3, a substrate 101 may be loaded on growth equipment,and a layer or pattern may be formed on the substrate 101 by using agroup II to VI compound semiconductor.

Examples of the growth equipment includes an E-beam evaporatorequipment, physical vapor deposition (PVD) equipment, chemical vapordeposition (CVD) equipment, plasma laser deposition (PLD) equipment, adual-type thermal evaporator, sputtering equipment, and metal organicchemical vapor deposition (MOCVD) equipment. However, the growthequipment is not limited thereto.

The substrate 101 may be a conductive or insulating substrate formed ofa material selected from the group consisting of Al₂O₃ (sapphire), GaN,SiC, ZnO, Si, GaP, InP, Ga₂O₃, and GaAs. A concave-convex structurehaving a lens or stripe shape may be formed on the substrate 101. Theconcave-convex structure may be a patterned structure or a roughstructure.

The thickness of the substrate 101 may be in the range from about 30 μmto about 500 μm. The thickness of the substrate 101 may be variedaccording to lapping and/or polishing.

In addition, a compound semiconductor layer may be formed on thesubstrate 101. The compound semiconductor layer may be a layer orpattern formed of a group II to VI compound semiconductor. For example,at least one of a ZnO layer, a buffer layer, and an undopedsemiconductor layer may be formed. The buffer layer or the undopedsemiconductor layer may be formed of a group III-V compoundsemiconductor. The buffer layer may function to reduce a latticeconstant difference from that of the substrate 101. The undopedsemiconductor layer may a less conductive layer than a first conductivetype semiconductor layer. The undoped semiconductor layer may be formedof an undoped GaN-based semiconductor.

A reflection layer 102 may be formed on the substrate 101 in differentregions of the substrate 101. A plurality of patterns may be formed asthe reflection layer 102 by a photoresist process using a mask, and thepatterns may be spaced apart from each other to form a circular orpolygonal shape. Alternatively, the reflection layer 102 may formed intoa pattern having a loop shape (open loop or closed loop) such as a ringshape, a band shape, and a frame shape; or a radial or polygonalpattern. However, the reflection layer 102 is not limited thereto.

The reflection layer 102 may be formed into a super lattice structure.For example, the reflection layer 102 may be formed into a distributedBragg reflector (DBR) structure by alternately stacking at least twolayers (such as AlN/GaN) having different refractive indexes at leastonce. A material of the reflection layer 102 includes an oxide-basedmaterial and/or a nitride-based material. The reflection layer 102 maybe formed of a metal having a high melting point. For example, thereflection layer 102 may be formed of at least one metal selected fromthe group consisting of W and Mo. Alternatively, the reflection layer102 may be formed into a multilayer structure such as a W/Mo stackedstructure. In addition, the reflection layer 102 may include a superlattice structure such as Si/Mo and Mo/Si. The reflection layer 102 maybe formed of a material durable at high temperature, for example, 1000□or higher and having at least 50% reflectivity. In addition, thereflection layer 102 has a structure of Omni-Directional Reflective(ODR) using at least metal layer such as Ti, Ta, W, Mo and alloythereof.

An absorption layer may be formed under the reflection layer 102 toabsorb laser light by using a material having a band gap smaller thanthat of the substrate 101. The absorption layer includes at least oneselected from the group consisting of ZnO, TiO₂, SiO₂, Si₃N₄, TiN, AlN,GaN, W, Ta, and Mo. Alternatively, the absorption layer may be formed ofa metallic material and may be formed in a reflection layer region.During a laser hole machining process, the absorption layer may absorblaser light to protect a light emitting structure layer. However, thisis a non-limiting example. Here, reflectivity with respect to a laserlight source may be varied according to the thickness of W and Mo.

The width of the reflection layer 102 and/or the width of the absorptionlayer may be in the range from about 2 μm to about 50 μm, and thethickness of the reflection layer 102 and/or the thickness of theabsorption layer may be in the range from about 10 Å to about 30000 Å.

Here, patterns of the reflection layer 102 disposed in different regionsmay be connected to each other. In this case, the reflection layer 102may function as a conductive pattern when a first electrode is formed.

Referring to FIG. 4, a first conductive type semiconductor layer 110 isformed on the substrate 101 or the compound semiconductor layer, and anactive layer 115 is formed on the first conductive type semiconductorlayer 110. A second conductive type semiconductor layer 120 is formed onthe active layer 115. Another semiconductor layer may be furtherdisposed on or under each of the layers. However, this is a non-limitingexample.

The reflection layer 102 is disposed at least on a lower part of thefirst conductive type semiconductor layer 110, and the lower surface ofthe first conductive type semiconductor layer 110 is an N-face having asurface roughness greater than that of a Ga-face. The reflection layer102 may extend from the lower surface to an inner part of the firstconductive type semiconductor layer 110.

The first conductive type semiconductor layer 110 may be formed of agroup III-V compound semiconductor doped with a first conductive typedopant, such as GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs,GaP, GaAs, GaAsP, or AlGaInP. The first conductive type semiconductorlayer 110 may be formed of a semiconductor material having acompositional formula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0x+y≦1).The first conductive type semiconductor layer 110 may be an N-typesemiconductor layer. The N-type semiconductor layer includes an N-typedopant such as Si, Ge, Sn, Se, or Te. The first conductive typesemiconductor layer 110 may function as an electrode contact layer andbe formed into a single-layer or multilayer structure. However, thefirst conductive type semiconductor layer 110 is not limited thereto.

The first conductive semiconductor layer 110 may have a super latticestructure in which different semiconductor layers are alternatelystacked. The super lattice structure may include a structure such as aGaN/InGaN structure or a GaN/AlGaN structure.

The active layer 115 is formed on the first conductive semiconductorlayer 110, and the active layer 115 may has at least one of a singlequantum well structure, a multi quantum well structure, a quantum wirestructure, and a quantum dot structure. The active layer 115 may beformed of a group III-V compound semiconductor material and have aperiod of well layer/barrier layer. For example, the active layer 115may have at least one of a period of InGaN well layer/GaN barrier layer,a period of InGaN well layer/AlGaN barrier layer, and a period of InGaNwell layer/InGaN barrier layer.

A first conductive type clad layer may be disposed between the firstconductive type semiconductor layer 110 and the active layer 115. Thefirst conductive type clad layer may be formed of a GaN-basedsemiconductor. The first conductive type clad layer may have a band gapgreater than that of the barrier layer within the active layer 115 andfunction to confine carriers.

A second conductive type clad layer may be disposed between the activelayer 115 and the second conductive type semiconductor layer 120. Thesecond conductive type clad layer may be formed of a GaN-basedsemiconductor. The second conductive type clad layer may have a band gapgreater than that of the barrier layer within the active layer 115 andfunction to confine carriers.

The second conductive type semiconductor layer 120 is disposed on theactive layer 115. The second conductive type semiconductor layer 120 maybe formed of a group III-V compound semiconductor doped with a secondconductive type dopant, such as GaN, AlN, AlGaN, InGaN, InN, InAlGaN,AlInN, AlGaAs, GaP, GaAs, GaAsP, or AlGaInP. The second conductive typesemiconductor layer 120 may be formed of a semiconductor material havinga compositional formula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1,0≦x+y≦1).

The second conductive type semiconductor layer 120 may has asingle-layer or multilayer structure. In the case where the secondconductive type semiconductor layer 120 has a multilayer structure, thesecond conductive type semiconductor layer 120 may have a super latticestructure such as AlGaN/GaN.

The second conductive type semiconductor layer 110 may be a P-typesemiconductor layer. The P-type semiconductor layer includes a P-typedopant such as Mg, Be, or Zn. The second conductive type semiconductorlayer 120 may function as an electrode contact layer, but is not limitedthereto.

The first conductive type semiconductor layer 110, the active layer 115,and the second conductive type semiconductor layer 120 may be defined asa light emitting structure layer 125. In addition, a third conductivetype semiconductor layer having a polarity opposite to that of thesecond conductive type may be formed on the second conductive typesemiconductor layer 120. The light emitting structure layer 125 may haveat least one of an N—P junction structure, a P—N junction structure, anN—P—N junction structure, and a P—N—P junction structure. Hereinafter, astructure in which the second conductive type semiconductor layer 120 isan upper layer of the light emitting structure layer 125 will bedescribed as an example.

Referring to FIG. 5, holes 105 are formed in the substrate 101. Theholes 105 may penetrate at least the substrate 101. The holes 105 may beformed to be connected to the reflection layer 102 by induced laserlight to the lower surface of the substrate 101. The holes 105 may belocated at the reflection layer 102 at positions corresponding to eachother. When the holes 105 are formed, the reflection layer 102 mayreflect laser light to protect the light emitting structure layer 125.

The holes 105 may have a diameter in the range from about 0.5 μm toabout 50 μm. The holes 105 may be formed in a line shape perpendicularto the lower surface of the substrate 101 or a non-linear shape. Forexample, the holes 105 may have a via hole structure or a through holestructure. The holes 105 may have a circular section or a polygonalshape. The diameter or width of the holes 105 may be varied according tothe positions of the holes 105 in the substrate 101.

The holes 105 may be formed after placing a protective sheet on thelight emitting structure layer 125 and turning the substrate 101 over toplace the light emitting structure layer 125 at a lower position.

Referring to FIGS. 5 and 6, the reflection layer 102 is removed. Aregion 102A from which the reflection layer 102 is removed is upper endsof the holes 105 so that the holes 105 are connected to a lower portionof the light emitting structure layer 125, that is, a lower portion ofthe first conductive type semiconductor layer 110.

The reflection layer 102 may be removed by wet etching. The wet etchingmay be performed by using an etchant selectively including ahydrofluoric acid (HF), a nitric acid (HNO₃), an acetic acid (CH₃COOH),a phosphoric acid (H₃PO₄), and a sulfuric acid (H₂SO₄). The wet etchingmay be formed by a different manner within the technical scope of theembodiment. If the reflection layer 102 has good conductivity, thereflection layer 102 may not be removed.

Second electrode parts 150 and 152 electrically connected to each otherare formed on the topside of the light emitting structure layer 125. Thesecond electrode parts 150 and 152 may be formed after the secondconductive type semiconductor layer 120 is formed. The second electrodeparts 150 and 152 may be formed before or after the holes 105 areformed. This sequence is a non-limiting example.

The second electrode parts 150 and 152 may be electrically connected tothe second conductive type semiconductor layer 120. For example, thesecond electrode parts 150 and 152 may be formed on the secondconductive type semiconductor layer 120. The second electrode parts 150and 152 may include a pad (150) and a second electrode (152). The secondelectrode parts 150 and 152 may be formed into a single layer or multilayers by using at least one selected from the group consisting of Ti,Al, Al alloy, In, Ta, Pd, Co, Ni, Si, Ge, Ag, Ag alloy, Au, Hf, Pt, Ru,Au, and an alloy thereof. The second electrode parts 150 and 152 mayinclude at least one pad 150. As shown in FIG. 2, the second electrode152 is electrically connected to the pad 150. The second electrode 152may have at least a branch or arm shape. For example, the secondelectrode 152 may have a loop, line, curve, polygonal, or circularshape. However, the second electrode 152 is not limited thereto.

A second electrode layer may be formed between the second electrodeparts 150 and 152 and the second conductive type semiconductor layer120. The second electrode layer may include a current diffusion layer ora transmittive conductive layer. The second electrode layer may includea transmittive oxide or nitride. For example, the second electrode layermay be formed into a single-layer or multilayer structure by using atleast one selected from the group consisting of ITO (indium tin oxide),IZO (indium zinc oxide), IZTO (indium zinc tin oxide), IAZO (indiumaluminum zinc oxide), IGZO (indium gallium zinc oxide), IGTO (indiumgallium tin oxide), AZO (aluminum zinc oxide), ATO (antimony tin oxide),GZO (gallium zinc oxide), IrOx, RuOx, RuOx/ITO, Ni, Ag, Ni/IrOx/Au, andNi/IrOx/Au/ITO. The second electrode layer may diffuse a current andsupply the diffused current to the second conductive type semiconductorlayer 120.

Referring to FIG. 7, first electrodes 160 are formed in the holes 105 ofthe substrate 101. The first electrodes 160 may be formed by formingmetal seeds and performing a plating process. Alternatively, the firstelectrodes 160 may be formed by filling a conductive material in theholes 105. However, the first electrodes 160 are not limited to suchmethods.

As many first electrodes 160 as the number of the holes 105 may beformed. The first electrodes 160 may be disposed under a light emittingregion of the light emitting device 100, for example, under the activelayer 115.

The first electrodes 160 may be formed in the holes 105 verticallyformed in the substrate 101 by using a metal including one or more ofCu, Ti, Cr, Ta, Al, In, Pd, Co, Ni, Ge, Ag, and Au, but is not limitedthereto.

The first electrodes 160 may be formed into a vertical line shape ornon-linear shape to connect the lower side of the first conductive typesemiconductor layer 110 and the lower side of the substrate 101. Thediameter or width of the first electrodes 160 disposed in the substrate101 may be about 0.5 μm to about 50 μm. The diameter or width of contactportions 162 of the first electrodes 160 may be in the range from about2 μm to about 50 μm, and the thickness of the contact portions 162 maybe in the range from about 10 Å to about 30000 Å. The contact portions162 may be upper ends of the first electrodes 160.

At least two of the contact portion 162 of the first electrodes 160 maybe connected to each other through a conductive layer that variesaccording to the pattern of the reflection layer 102.

The diameter of width of the contact portions 162 of the firstelectrodes 160 may be may be greater than at least that of the firstelectrodes 160 disposed in the substrate 101, but not limited thereto.

As shown in FIG. 2, the first electrodes 160 may be arranged under aregion of the light emitting structure layer 125 at regular, random, orirregular intervals. However, the first electrodes 160 are not limitedthereto. The intervals and arrangement of the first electrodes 160 maycorrespond to current efficiency and the pattern of the second electrode152 and may be varied according to the pattern of the second electrode152.

A first electrode layer 165 may be formed under the substrate 101 toconnect lower ends of the electrodes 160.

The first electrode layer 165 may be formed of the same material as afirst electrode material or a material different from the firstelectrode material. The first electrode layer 165 may be formed into asingle-layer or multilayer structure by using the same metal used toform the first electrodes 160. The first electrode layer 165 mayfunction as a reflection layer or a bonding layer. The first electrodelayer 165 may be formed on the lower surface of the substrate 101entirely or partially and be formed into a single pattern or a pluralityof patterns.

The lower surface of the substrate 101 may be treaded by lapping and/orpolishing, but not limited thereto.

Thereafter, an isolation etching process may be performed on boundaries(for example, channel regions) between chips. Then, the chips may beseparated from each other by a cutting or/and breaking process. Here,the isolation etching process is performed to separate the chips and maybe performed before or after the process of forming electrodes. However,the processes are not limited to this sequence.

FIG. 8 is a side sectional view illustrating a light emitting device100A according to a second embodiment. In the following description ofthe second embodiment, the same described as that made in the firstembodiment will not be repeated.

Referring to FIG. 8, the light emitting device 100A includes a substrate101 having a concave-convex structure 103, a first semiconductor layer104, a light emitting structure layer 125, second electrode parts 150and 152, first electrodes 160, and a first electrode layer 165.

The substrate 101 may be formed of a material selected from the groupconsisting of Al₂O₃ (sapphire), GaN, SiC, ZnO, GaP, InP, Ga₂O₃, andGaAs. A concave-convex structure having a lens or stripe shape may beformed on the substrate 101. In addition, a first semiconductor layer104 may be formed on the substrate 101. The first semiconductor layer104 may be a layer or pattern formed of a group II to VI compoundsemiconductor. For example, the first semiconductor layer 104 mayinclude at least one of a ZnO layer (not shown), a buffer layer (notshown), and an undoped semiconductor layer (not shown).

The light emitting structure layer 125 is formed on the firstsemiconductor layer 104 by using a group III-V compound semiconductor.The light emitting structure layer 125 includes a first conductive typesemiconductor layer 110, an active layer 115, and a second conductivetype semiconductor layer 120.

The second electrode parts 150 and 152 are electrically connected to thesecond conductive type semiconductor layer 120. A detailed descriptionthereof will be omitted.

The plurality of first electrodes 160 are disposed in a region under theactive layer 115. The first electrodes 160 are vertically disposed inthe substrate 101. Contact portions 162 of the first electrodes 160 aredisposed in regions where a reflection layer (refer to FIGS. 3 to 6).The reflection layer is formed and removed by etching after the firstsemiconductor layer 104 is formed.

The diameter or width of the contact portions 162 of the firstelectrodes 160 may be greater than at least the diameter or width of thefirst electrodes 160 disposed in the substrate 101, and the diameter orwidth of the first electrodes 160 disposed in the substrate 101 may bevaried according to regions of the substrate 101.

The concave-convex structure 103 is formed at a lower part of thesubstrate 101. The concave-convex structure 103 includes concave partsand convex parts that are alternatively arranged. Examples of the shapeof the concave-convex structure 103 include a concave-convex pattern, atexture pattern, and a rough pattern. The concave-convex structure 103may be formed by performing a dry etching process and/or a wet etchingprocess on the lower surface of the substrate 101. The concave parts andconvex parts of the concave-convex structure 103 may be arranged atregular or irregular intervals and may have a polygonal shape or aspherical shape.

The first electrode layer 165 is disposed on the lower side of thesubstrate 101 and has a shape corresponding to the shape of theconcave-convex structure 103. Therefore, the first electrode layer 165can reflect light incident on the substrate 101, and a critical angle oflight can be varied by the concave-convex structure 103 to improve lightextraction efficiency.

FIG. 9 is a side sectional view illustrating a light emitting device100B according to a third embodiment.

Referring to FIG. 9, the light emitting device 100B includes a substrate101, a first semiconductor layer 104, a light emitting structure layer125, first electrodes 160, a first electrode layer 165, a secondelectrode layer 140, and a pad 150.

The substrate 101 may be formed of a material selected from the groupconsisting of Al₂O₃ (sapphire), GaN, SiC, ZnO, Si, GaP, InP, Ga₂O₃, andGaAs.

A light extraction structure 106 may be disposed between the substrate101 and the first semiconductor layer 104. The light extractionstructure 106 may be formed by partially etching the topside of thesubstrate 101 or be formed of an additional material. The lightextraction structure 106 includes a light diffusion structure. The lightextraction structure 106 may include at least one of a metal dotstructure, an insulating dot structure, and a semiconductor dotstructure. The light extraction structure 106 may be formed of amaterial having a refractive index different from that of the firstsemiconductor layer 104. However, the light extraction structure 106 isnot limited thereto.

The light extraction structure 106 may be disposed between a secondsemiconductor layer 111 and a third semiconductor layer 112 of a firstconductive type semiconductor layer 110. The light extraction structure106 may diffuse a current.

The first semiconductor layer 104 may be a layer or pattern formed of agroup II to VI compound semiconductor. For example, the firstsemiconductor layer 104 may include at least one of a ZnO layer (notshown), a buffer layer (not shown), and an undoped semiconductor layer(not shown).

The first conductive type semiconductor layer 110 includes the secondsemiconductor layer 111 and the third semiconductor layer 112. Thesecond semiconductor layer 111 and the third semiconductor layer 112 mayhave different dopant concentrations, thicknesses, or compositionformulas. The dopant concentration of the second semiconductor layer 111may be lower than that of the third semiconductor layer 112. Forexample, the second semiconductor layer 111 may be a low conductivesemiconductor layer, and the third semiconductor layer 112 may be moreconductive than the second semiconductor layer 111. The secondsemiconductor layer 111 may be formed of an AlGaN layer, and the thirdsemiconductor layer 112 may be formed of a GaN layer. A stackedstructure of the second semiconductor layer 111 and the thirdsemiconductor layer 112 may be repeated at least twice (two periods),but not limited thereto.

The stacked structure of the second semiconductor layer 111 and thethird semiconductor layer 112 may be a super lattice structure (SLS)formed of a material selected from the group consisting of GaN, InN,AlN, InGaN, AlGaN, InAlGaN, SiO₂, SiO_(x), SiN₂, SiN_(X), Si0_(x)N_(y),and a metal material. In the super lattice structure, at least twodifferent layers are alternately repeated at least two times (twoperiods). For example, a stacked structure of InGaN/GaN is repeated.Each layer of the super lattice structure may have a thickness of aboutseveral angstroms (Å) or more.

Alternatively, the stacked structure of the second semiconductor layer111 and the third semiconductor layer 112 may be formed by alternatelystacking at least two layers having different refractive indexes so thatthe stacked layers may function as reflection layers. For example, astructure of GaN layer/AlN layer may be repeatedly stacked at least twoperiods to form a distributed Bragg reflector (DBR).

Contact portions 162 of the first electrodes 160 may make contact withthe second semiconductor layer 111 and/or the third semiconductor layer112, but are not limited thereto.

The second electrode layer 140 is disposed on the second conductive typesemiconductor layer 120. The second electrode layer 140 includes amaterial different from the semiconductor layers, for example, aconductive material such as a metal oxide or a metal nitride. The secondelectrode layer 140 may be formed of at least one selected from thegroup consisting of ITO (indium tin oxide), IZO (indium zinc oxide),IZTO (indium zinc tin oxide), IAZO (indium aluminum zinc oxide), IGZO(indium gallium zinc oxide), IGTO (indium gallium tin oxide), AZO(aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zincoxide), IrOx, RuOx, RuOx/ITO, Ni, Ag, Ni/IrOx/Au, and Ni/IrOx/Au/ITO.

The width of the second electrode layer 140 may be smaller than at leastthe width of the second conductive type semiconductor layer 120. Atleast one of the second electrode layer 140 and the second conductivetype semiconductor layer 120 may include a rough top surface.

At least one pad 150 is disposed on the second electrode layer 140, andpower supplied to the pad 150 may be diffused by the second electrodelayer 140. An electrode may be further connected to the pad 150.However, it is a non-limiting example.

The side surfaces of the light emitting structure layer 125 may beoblique to the lower surface of the substrate 101, and the lower surfaceof the active layer 115 may be smaller than the lower surface of thefirst conductive type semiconductor layer 110. In addition, the firstelectrodes 160 may be disposed in a region under the active layer 115 orthe first conductive type semiconductor layer 110.

FIGS. 10 and 11 are views for explaining processed of manufacturing alight emitting device according to a fourth embodiment. FIG. 10 is viewfor explaining elements modified from those explained with reference toFIGS. 3 and 4. Descriptions of other processes are the same as thoseexplained with reference to FIGS. 3 to 7.

Referring to FIG. 10, a first layer 131 and a second layer 131 aredisposed between a substrate 101 and a first conductive typesemiconductor layer 110. The second layer 131 may receive laser lightand function as an absorption layer. The second layer 132 may functionas a reflection layer to reflect laser light. The first layer 131functioning as an absorption layer may include at least one selectedfrom the group consisting of ZnO, TiO₂, SiO₂, Si₃N₄, TIN, AlN, GaN, W,Ta, and Mo. The second layer 132 may include a material (oxide-based ornitride-based) or a structure such as a GaN/AlGaN super latticestructure, W, Mo, a W/Mo structure, a Si/Mo super lattice structure, anda Mo/Si super lattice structure. The first layer 131 may be formed of ametal having a high melting point. For example, the first layer 131 maybe formed of at least one metal selected from the group consisting of Wand Mo. In addition, the first layer 102 has a structure ofOmni-Directional Reflective (ODR) using at least metal layer such as Ti,Ta, W, Mo and alloy thereof.

The reflectivity of the first layer 131 may be 50% or higher for a givenlaser source, but is not limited thereto. In another example, the firstlayer 131 and the second layer 132 may have different widths. Forexample, a width of the second layer 132 may be wider than the firstlayer 131.

Referring to FIG. 11, holes are formed in the substrate 101 using alaser, and the first layer 131 is removed by wet etching. Contactportions 162 of first electrodes 160 may be formed in regions 102A fromwhich the first layer 131 is removed. The contact portions 162 of thefirst electrodes 160 may be disposed under the second layer 132 and makecontact with the first conductive type semiconductor layer 110. Thesecond layer 132 is less conductive than the first conductive typesemiconductor layer 110 so that a current from the contact portions 162of the first electrodes 160 is blocked by the second layer 132. Thus, acurrent from the contact portions 162 of the first electrodes 160 can bediffused in the first conductive type semiconductor layer 110 by thesecond layer 132. In another example, if the width of the second layer132 is greater than the width of the first layer 131, the width of thesecond layer 132 may be adjusted be smaller than the width of thecontact portions 162 of the first electrodes 160 to improve currentdiffusion efficiency.

FIGS. 12 to 14 are views for explaining processes of manufacturing alight emitting device according to a fifth embodiment.

Referring to FIG. 12, an absorption layer 102B is formed on a substrate101 or under a first conductive type semiconductor layer 110. The lengthof the absorption layer 102B may be about ½ to about ⅕ the width of alight emitting structure layer. The length of the absorption layer 102Bmay be enough to connect at least two second electrodes. The absorptionlayer 102B may have only an absorption function or be formed into anabsorption layer/reflection layer stacked structure. However, theabsorption layer 102B is not limited thereto.

Referring to FIGS. 13 and 14, holes 105 are formed in the substrate 101at positions under the absorption layer 102B, and the absorption layer102B is removed. The absorption layer 102B may be removed by a wetetching process. In this case, a part of the absorption layer 102B maynot be removed by the wet etching process.

First electrodes 160 are filled in the holes 105 so that contactportions 162 of the first electrodes 160 can make contact with the firstconductive type semiconductor layer 110. The contact portions 162 of thefirst electrodes 160 may include bridge portions 162A connecting thecontact portions 162.

As shown in FIG. 4, the bridge portions 162A are a conductive layerconnecting the plurality of first electrodes 160. The number of thebridge portions 162A is at least two, and the bridge portions 162A mayconnect first electrodes 160 disposed in different regions. FIG. 13 is aside sectional view taken along line B-B of FIG. 14.

FIG. 15 is a side sectional view illustrating a light emitting deviceaccording to a sixth embodiment.

Referring to FIG. 15, the width of lower portions 161 of firstelectrodes 160 is greater than the width of center parts of the firstelectrodes 160. The lower portions 161 of the first electrodes 160 aresecond contact portions, and contact portions 162 of the firstelectrodes 160 are first contact portions. The lower portions 161 of thefirst electrodes 160 become wider as it goes down in a substrate 101 sothat contact areas between the lower portions 161 and a first electrodelayer 165 can be increased for improving electrical reliability.

A second electrode layer 140 is formed on a second conductive typesemiconductor layer 120. The second electrode layer 140 includes atransmittive oxide or a transmittive nitride and is conductive.

The second electrode layer 140 may include a rough surface as a lightextraction structure S6 having a regular or irregular concave-convexstructure. The light extraction structure S6 of the second electrodelayer 140 may vary a critical angle of incident light to improve lightextraction efficiency.

The second electrode layer 140 may make contact with the lower sides ofsecond electrode parts 150 and 152 to diffuse a current.

FIG. 16 is a side sectional view illustrating a light emitting deviceaccording to a seventh embodiment.

Referring to FIG. 16, in the light emitting device, contact portions 162of first electrodes 160 may include rough surfaces. The top surfaces ofthe contact portions 162 may make contact with rough surfaces S7 of afirst conductive type semiconductor layer 110. Owing to the roughsurfaces S7, light extraction efficiency and current injectionefficiency may be improved.

The rough surfaces S7 are formed on the lower surface of the firstconductive type semiconductor layer 110 by performing a wet etchingprocess on such a structure as shown in FIGS. 5 and 6. The lower surfaceof the first conductive type semiconductor layer 110 is an N-face havinga surface roughness greater than that of a Ga-face. Owing to the roughsurfaces S7, current injection efficiency and light extractionefficiency can be improved.

The thickness of a first semiconductor layer 104A may be smaller thanthat of an absorption layer, and the contact portions 162 of the firstelectrodes 160 may be disposed in the first semiconductor layer 104A.According to the thicknesses of the first semiconductor layer 104A andthe absorption layer, contact positions of the contact portions 162 ofthe first electrodes 160 may be varied.

FIG. 17 is a side sectional view illustrating a light emitting deviceaccording to an eighth embodiment.

Referring to FIG. 17, an absorption layer 102 of the light emittingdevice is partially removed by an etching process, and thus parts of theabsorption layer 102 are left. Contact portions 162 of first electrodes160 are disposed under the absorption layer 102 and make contact withinner sides of a first conductive type semiconductor layer 110. In thisway, since the contact portions 162 of the first electrodes 160 makecontact with the absorption layer 102 and the first conductive typesemiconductor layer 110, a current can be diffused. The width of theabsorption layer 102 may be different from the width of the contactportions 162 of the first electrodes 160. For example, the width of thecontact portions 162 of the first electrodes 160 may be greater than thewidth of the absorption layer 102.

A second electrode layer 140 is disposed on a second conductive typesemiconductor layer 120, and the width of the second electrode layer 140is smaller than at least the width of the second conductive typesemiconductor layer 120.

FIG. 18 is a view illustrating a light emitting device package 30according to an embodiment.

Referring to FIG. 18, the light emitting device package 30 includes: abody 20; first and second lead electrodes 31 and 32 disposed on the body20; the light emitting device 100 of the previous embodiment disposed onthe body 20 and electrically connected to the first and second leadelectrodes 31 and 32; and a molding member 40 enclosing the lightemitting device 100.

The body 20 may be formed of a material such as silicon, syntheticresin, and metal. A cavity 25 may be formed in an upper part of the body20. The topside of the cavity 25 may be opened, and the first and secondlead electrodes 31 and 32 may be disposed on the bottom side of thecavity 25. Lateral surfaces of the cavity 25 may be oblique or verticalto the lower surface of the cavity 25, but are not limited thereto. Thecavity 25 of the body 20 may have a stepped structure. Alternatively,the body 20 may not include the cavity 25 and have a flat top surface.

The first and second lead electrodes 31 and 32 are electricallyseparated from each other and are configured to supply power to thelight emitting device 100. In addition, the first and second leadelectrodes 31 and 32 may be formed of a metal plate such as a leadframe, but are not limited thereto. The first and second lead electrodes31 and 32 may reflect light emitted from the light emitting device 100to improve optical efficiency and may dissipate heat generated from thelight emitting device 100.

The light emitting device 100 may be disposed on the body 20 or on thefirst or second lead electrodes 31 or 32.

The light emitting device 100 may be electrically connected to the firstlead electrode 31 through a wire and to the second lead electrode 32 bydie bonding.

The molding member 40 may include silicon or a resin such as epoxy. Themolding member 40 may be disposed in the cavity 25. The molding member40 may cover the light emitting device 100 to protect the light emittingdevice 100. In addition, a phosphor may be contained in the moldingmember 40 to change the wavelength of light emitted from the lightemitting device 100.

<Lighting System>

The semiconductor light emitting device or a light emitting devicepackage according to an embodiment may be provided in plurality. Theplurality of light emitting devices or the light emitting devicepackages may be arrayed on the board. Optical members such as a lightguide plate, a prism sheet, and a diffusion sheet may be disposed on apath of the light emitted from the light emitting device. The lightemitting device package, the board, and the optical members may serve asa lighting unit. The lighting unit may be manufactured in a top viewtype or a side view type. Thus, the lighting unit may be provided asdisplay devices for a portable terminal, a notebook computer, etc, orvariously applied to the lighting device, the indicating device, etc.Also, in another embodiment, the lighting unit may be realized as alighting system including the light emitting device or the lightemitting device package according to the above-described embodiments.The lighting system may include display devices illustrated in FIGS. 19and 20, a lighting device illustrated in FIG. 21, illumination lamps,signal lights, car headlights, electronic displays, and the like.

FIG. 19 is an exploded perspective view illustrating a display deviceaccording to an embodiment.

Referring to FIG. 19, a display device 1000 according to the embodimentmay include a light guide plate 1041, a light emitting module 1031providing light to the light guide plate 1041, a reflection member 1022under the light guide plate 1041, an optical sheet 1051 on the lightguide plate 1041, a display panel 1061 on the optical sheet 1051, and abottom cover 1011 storing the light guide 1041, the light emittingmodule 1031, and the reflection member 1022; however, it is not limitedto this.

The bottom cover 1011, the reflection sheet 1022, the light guide plate1041, and the optical sheet 1051 may be defined as a light unit 1050.

The light guide plate 1041 serves to diffuse light for convergence to asurface light source. The light guide plate 1041 is formed withtransmittive material and, e.g., may include one of acrylic resin suchas polymethyl metaacrylate (PMMA), polyethylene terephthlate (PET), polycarbonate (PC), cycloolefin copolymer (COC), and polyethylenenaphthalate (PEN) resins.

The light emitting module 1031 provides light to at least one side ofthe light guide plate 1041 and ultimately acts as a light source of thedisplay device.

At least one light emitting module 1031 is included, and it may providelight directly or indirectly at one side of the light guide plate 1041.The light emitting module 1031 includes a board 1033 and the lightemitting device package 30 according to the above-disclosed embodiment.The light emitting device package 30 may be arrayed at predeterminedintervals on the board 1033.

The board 1033 may be a Printed Circuit Board (PCB) including a circuitpattern (not illustrated). However, the board 1033 may include not onlythe typical PCB but also a metal core PCB (MCPCB) and a flexible PCB(FPCB), and it is not limited to this. In the case that the lightemitting device package 30 is installed on the side of the bottom cover1011 or on a heat radiating plate, the board 1033 may be eliminated.Herein, a part of the heat radiating plate may be contacted to an uppersurface of the bottom cover 1011.

The plurality of light emitting device packages 30 may be installed onthe board 1033 so that a light-emitting surface is separated from thelight guide plate 1041 by a predetermined distance, and there is nolimit for this. The light emitting device package 30 may provide lightto a light-entering part, i.e., one side, of the light guide plate 1041directly or indirectly, and there is no limit for this.

The reflection member 1022 may be disposed under the light guide plate1041. The reflection member 1022 reflects the light incident to thelower surface of the light guide plate 1041 in an upward direction sothat brightness of the light unit 1050 may be improved. The reflectionmember 1022 may be formed with, e.g., PET (Polyethylene terephthalate),PC, PVC (polyvinyl chloride) resins; however, it is not limited to this.The reflection member 1022 may be the upper surface of the bottom cover1011; however, there is no limit for this.

The bottom cover 1011 may store the light guide plate 1041, the lightemitting module 1031, and the reflection member 1022. To this end, thebottom cover 1011 may be provided with a storing unit 1012 having ashape of a box whose upper surface is open, and there is not limit forthis. The bottom cover 1011 may be combined with a top cover, and thereis no limit for this.

The bottom cover 1011 may be formed with metal material or resinmaterial and may be fabricated using processes of press or extrusionmolding. The bottom cover 1011 may also include metal or non-metalmaterial having good thermal conductivity, and there is no limit forthis.

The display panel 1061 is, e.g., an LCD panel, and includes transmittivefirst and second substrates, and a liquid crystal layer between thefirst and second substrates. On at least one side of the display panel1061, a polarizing plate may be attached; however, the attachingstructure is not limited to this. The display panel 1061 displaysinformation by the light which passes through the optical sheet 1051.The display device 1000 may be applied to various cell phones, monitorsof notebook computers, monitors of laptop computers, and televisions.

The optical sheet 1051 is disposed between the display panel 1061 andthe light guide plate 1041 and includes at least one translucent sheet.The optical sheet 1051 may include at least one of, e.g., diffusionsheet, horizontal and vertical prism sheets, and brightness enhancementsheet. The diffusion sheet diffuses the incident light. The horizontalor/and vertical prism sheet concentrates the incident light to a displayregion. The brightness enhancement sheet reuses lost light to enhancebrightness. A protection sheet may be disposed on the display panel1061, and there is no limit for this.

Herein, on the light path of the light emitting module 1031, the lightguide plate 1041 and the optical sheet 1051 may be included as opticalmembers; however, there is no limit for this.

FIG. 20 is a diagram illustrating a display device according to anembodiment.

Referring to FIG. 20, a display device 1100 includes a bottom cover1152, a board 1120, an optical member 1154, and a display panel 1155.Herein, the above-disclosed light emitting device packages 30 arearrayed on the board 1120.

The board 1120 and the light emitting device package 30 may be definedas a light emitting module 1060. The bottom cover 1152, at least onelight emitting module 1060, and the optical member 1154 may be definedas a light unit.

The bottom cover 1152 may be provided with a storing unit 1153, andthere is no limit for this.

Herein, the optical member 1154 may includes at least one of the lens,light guide plate, diffusion sheet, horizontal and vertical prismsheets, and brightness enhancement sheet. The light guide plate may beformed with PC material or polymethyl metaacrylate (PMMA) material, andthis light guide plate may be eliminated. The diffusion sheet diffusesthe incident light. The horizontal or/and vertical prism sheetconcentrates the incident light to the display region. The brightnessenhancement sheet reuses lost light to enhance brightness.

The optical member 1154 is disposed on the light emitting module 1060.The optical member 1154 converts the light emitted from the lightemitting module 1060 to the surface light source, or performs diffusingand concentrating light.

FIG. 21 is a perspective view illustrating an lighting device accordingto an embodiment.

Referring to FIG. 21, an illumination device 1500 may include a case1510, a light emitting module 1530 installed to the case 1510, and aconnection terminal 1520 installed to the case 1510 and provided withpower from an external power source.

It is preferable to form the case 1510 with material which has good heatradiation characteristics. For instance, the case 1510 may be formedwith metal material or resin material.

The light emitting module 1530 may include a board 1532 and the lightemitting device package 30 according to the embodiment installed on theboard 1532. The plurality of light emitting device packages 30 may bearrayed in a matrix form or may be arrayed being separated from eachother at predetermined intervals.

The board 1532 may be an insulator where a circuit pattern is printed.For instance, the board 1532 may include the PCB, metal core PCB,flexible PCB, ceramic PCB, and FR-4 board.

The board 1532 may also be formed with material which efficientlyreflects light, or its surface may be coated with color, e.g., white andsilver, which efficiently reflects light.

At least one light emitting device package 30 may be installed on theboard 1532. Each of the light emitting device packages 30 may include atleast one Light Emitting Diode (LED) chip. The LED chip may include alight emitting diode of visible light such as red, green, blue, or whiteor a UV light emitting diode which emits Ultra Violet (UV).

A combination of various light emitting device packages 30 may bedisposed in the light emitting module 1530 for obtaining color tone andbrightness. For instance, for securing high Color Rendering Index (CRI),a white light emitting diode, a red light emitting diode, and a greenlight emitting diode may be combined and disposed.

The connection terminal 1520 may be electrically connected to the lightemitting module 1530 to supply power. The connection terminal 1520 isscrewed to be connected to the external power source in a socket method;however, there is no limit for this. For instance, the connectionterminal 1520 may be formed as a pin shape to be inserted into theexternal power source or may be connected to the external power sourceby a wire.

According to an embodiment, there is provided a method of manufacturinga light emitting device. The method includes: forming a plurality offirst layers on a substrate at predetermined intervals; forming aplurality of compound semiconductor layers on the substrate, thecompound semiconductor layers including a first conductive typesemiconductor layer, an active layer, and a second conductive typesemiconductor layer; forming a plurality of holes in the substrate toexpose the first layers; forming first electrodes in the holes; andforming a first electrode layer at a bottom side of the substrate toconnect a plurality of lower ends of the first electrodes.

According to the embodiments, an additional region is not necessary forforming a pad used to supply power to the first conductive typesemiconductor layer, light emitting area and optical efficiency can beincreased as compared with an LED chip having a horizontal electrodestructure. Therefore, the light emitting device, the light emittingdevice package, and the lighting system of the embodiments may haveimproved reliability.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

1. A light emitting device comprising: a substrate; a light emittingstructure layer comprising a first conductive type semiconductor layer,an active layer on the first conductive type semiconductor layer, and asecond conductive type semiconductor layer on the active layer; a secondelectrode on the light emitting structure layer; a first electrodedisposed in the substrate and extended from a lower part of thesubstrate to a lower part of the first conductive type semiconductorlayer, the first electrode being disposed under a region of the activelayer; a contact portion having a width wider than a width of the firstelectrode disposed in the substrate and disposed at the lower part ofthe first conductive type semiconductor layer; and a first electrodelayer disposed under the substrate and connected to the first electrode.2. The light emitting device according to claim 1, wherein the firstelectrode is provided in plurality, the contact portion is provided inplurality, and at least one of the plurality of contact portions iscloser to an edge part of the first conductive type semiconductor layerthan to a center part of the first conductive type semiconductor layer.3. The light emitting device according to claim 2, wherein the firstelectrode layer connects lower portions of the plurality of firstelectrode.
 4. The light emitting device according to claim 3, wherein awidth of a lower surface of the first electrode layer is equal to ornarrower than a lower surface of the substrate and is wider than widthof a lower surface of the first conductive type semiconductor layer. 5.The light emitting device according to claim 1, further comprising afirst semiconductor layer formed of a group II to VI element anddisposed between the substrate and the light emitting structure layer,wherein at least one of the first electrode and the contact portion isdisposed in the first semiconductor layer.
 6. The light emitting deviceaccording to claim 4, wherein at least one of lower and upper surfacesof the substrate includes a concave-convex structure.
 7. The lightemitting device according to claim 1, further comprising at least one ofan absorption layer and a reflection layer between the contact portionand the first conductive type semiconductor layer.
 8. The light emittingdevice according to claim 2, further comprising a bridge portionconnecting between the plurality of contact portions.
 9. The lightemitting device according to claim 1, wherein contact surfaces of thecontact portion and the first conductive type semiconductor layer arerough.
 10. The light emitting device according to claim 1, furthercomprising a second electrode layer on between the second conductivetype semiconductor layer and the second electrode.
 11. A light emittingdevice comprising: a transmittive substrate; a first electrode layerunder the substrate; a light emitting structure layer comprising a firstconductive type semiconductor layer, an active layer on the firstconductive type semiconductor layer, and a second conductive typesemiconductor layer on the active layer; a plurality of first electrodesdisposed in the substrate and extended from the first electrode layer toa lower part of the first conductive type semiconductor layer; a secondelectrode layer on the light emitting structure layer; a secondelectrode on the second electrical layer; and a contact portioncontacted with the lower part of the first conductive type semiconductorlayer and having a width different from a width of the first electrodedisposed in the substrate.
 12. The light emitting device according toclaim 11, wherein the first conductive type semiconductor layercomprises: a first semiconductor layer having a low conductivity anddisposed between the substrate and the active layer; and a secondsemiconductor layer having a conductivity higher than a conductivity ofthe first semiconductor layer and disposed between the firstsemiconductor layer and the active layer.
 13. The light emitting deviceaccording to claim 11, wherein a lower portion of the first electrode isconnected to the contact portion, and the lower portion of the firstelectrode and the contact portion has a width wider than a width of thefirst electrode disposed in the substrate.
 14. The light emitting deviceaccording to claim 11, wherein at least one of top and lower surfaces ofthe substrate includes a concave-convex structure.
 15. The lightemitting device according to claim 11, wherein a size of a lower surfaceof the first electrode layer is smaller than a size of a lower surfaceof the substrate and is greater than a size of a lower surface of theactive layer.
 16. The light emitting device according to claim 11,wherein the first electrode layer includes a reflection layer and thesecond electrode layer includes a transmittive layer.
 17. The lightemitting device according to claim 11, wherein the light emittingstructure layer comprises at least one oblique lateral side.
 18. Thelight emitting device according to claim 11, wherein at least a portionof the second electrode is overlapped with the first electrodes in avertical direction, and further comprising at least one of an absorptionlayer and a reflection layer between the contact portion and the firstconductive type semiconductor layer.
 19. The light emitting deviceaccording to claim 11, wherein a top surface of the substrate extendsoutward from a lateral side of the light emitting structure layer.
 20. Alight emitting device package comprising: a body; a plurality of leadelectrodes on the body; a light emitting device on at least one of thelead electrodes; and a molding member covering the light emittingdevice, wherein the light emitting device comprises: a substrate; alight emitting structure layer comprising a first conductive typesemiconductor layer, an active layer on the first conductive typesemiconductor layer, and a second conductive type semiconductor layer onthe active layer; a second electrode on the light emitting structurelayer; a first electrode disposed in the substrate and extended from alower part of the substrate to a lower part of the first conductive typesemiconductor layer, the first electrode being disposed under a regionof the active layer; a contact portion having a width wider than a widthof the first electrode disposed in the substrate and disposed at thelower part of the first conductive type semiconductor layer; and a firstelectrode layer disposed under the substrate and connected to the firstelectrode.